Portable monitoring unit

ABSTRACT

A sensor system that provides an adjustable threshold level for the sensed quantity is described. The adjustable threshold allows the sensor to adjust to ambient conditions, aging of components, and other operational variations while still providing a relatively sensitive detection capability for hazardous conditions. The adjustable threshold sensor can operate for extended periods without maintenance or recalibration. A portable monitoring unit working in communication with the sensor system provides immediate communication of conditions detected by the sensors. The portable monitoring unit allows building or complex management to be in communication with a sensor system at all times without requiring someone to be physically present at a monitoring site. The portable monitoring unit can be equipped with an auditory device for alerting management or a screen for displaying pertinent information regarding an occurring situation so that management can quickly identify and resolve the problem. In addition, the portable monitoring unit can also be equipped with function keys that allow the portable monitoring unit to send instructions back to the sensor system. In one embodiment, the portable monitoring unit also includes a second transceiver for communications over a short wave radio frequency, or with a cellular phone system.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sensor in a wired or wireless sensorsystem for monitoring potentially dangerous or costly conditions suchas, for example, smoke, temperature, water, gas and the like. It alsorelates to a portable monitoring unit for monitoring conditions presentin a building, or complex.

2. Description of the Related Art

Maintaining and protecting a building or complex and its occupants isdifficult and costly. Some conditions, such as fires, gas leaks, etc.,are a danger to the occupants and the structure. Other malfunctions,such as water leaks in roofs, plumbing, etc., are not necessarilydangerous for the occupants, but can, nevertheless, cause considerabledamage. In many cases, an adverse condition such as water leakage, fire,etc., is not detected in the early stages when the damage and/or dangeris relatively small. This is particularly true of apartment complexeswhere there are many individual units and supervisory and/or maintenancepersonnel do not have unrestricted access to the apartments. When a fireor other dangerous condition develops, the occupant can be away fromhome, asleep, etc., and the fire alarm system can not signal an alarm intime to avoid major damage or loss of life.

Sensors can be used to detect such adverse conditions, but sensorspresent their own set of problems. For example, adding sensors, such as,for example, smoke detectors, water sensors, and the like in an existingstructure can be prohibitively expensive due to the cost of installingwiring between the remote sensors and a centralized monitoring deviceused to monitor the sensors. Adding wiring to provide power to thesensors further increases the cost. Moreover, with regard to firesensors, most fire departments will not allow automatic notification ofthe fire department based on the data from a smoke detector alone. Mostfire departments require that a specific temperature rate-of-rise bedetected before an automatic fire alarm system can notify the firedepartment. Unfortunately, detecting fire by temperature rate-of-risegenerally means that the fire is not detected until it is too late toprevent major damage.

Compounding this problem, alarm systems do not provide actual measureddata (e.g., measured smoke levels) to a remote monitoring panel. Thetypical fire alarm system is configured to detect a threshold level ofsmoke (or temperature) and trigger an alarm when the threshold isreached. Unfortunately, the threshold level must be placed relativelyhigh to avoid false alarms and to allow for natural aging of components,and to allow for natural variations in the ambient environment. Settingthe threshold to a relatively high level avoids false alarms, butreduces the effectiveness of the sensor and can unnecessarily put peopleand property at risk. Such a system is simple to operate but does notprovide a sufficient “early warning” capability to allow supervisorypersonnel to respond to a fire in the very early stages. Moreover, evenin a system with central or remote monitoring capability, someone mustbe present at all times at the monitoring site to see what is happening,increasing the cost of monitoring.

SUMMARY

These and other problems are solved by providing a sensor system thatprovides sensor information to a portable monitoring unit (“PMU”) foralerting building or complex management, or other responsible parties,to a potential problem detected by the sensor system.

The PMU allows building or complex management to be in communicationwith the sensor system without requiring someone to be physicallypresent at a monitoring site. In this respect, when a sensorcommunicates an alarm or other warning, the building or complexmanagement will be quickly apprised of the situation. The early warningallows management to assess the situation and take early action, therebyreducing harm to the structure and any occupants present.

In one embodiment, the PMU operates in communication with the sensormonitoring system of a building, apartment, office, residence, etc. Ifthe sensor system determines that the condition is an emergency (e.g.,smoke has been detected), then the sensor system sends an alert messageto the PMU. If the sensor system determines that the situation warrantsreporting, but is not an emergency (e.g., low battery), then the sensorsystem can send a warning message to the PMU or can log the data forlater reporting. Non-emergency information reported by the sensors canlatter be sent to the PMU upon request, or upon the occurrence of apre-defined event. In this way, building management can be informed ofthe conditions in and around the building without having to be presentat a central location. In one embodiment, the sensor system detects andreports conditions such as, for example, smoke, temperature, humidity,moisture, water, water temperature, carbon monoxide, natural gas,propane gas, other flammable gases, radon, poison gasses, etc.

In one embodiment, the PMU can be small enough to be held in a hand,carried in a pocket, or clipped to a belt. In one embodiment, the PMUhas a display screen for displaying communications. In one embodimentthe PMU has one or more buttons or function keys for aiding incommunication with the monitoring computer, repeaters or sensors. Thefunction keys can be used to communicate one or more of the following:ACKNOWLEDGE receipt of message from monitoring computer; OK—situationhas been taken care of or is a false alarm; PERFORM DIAGNOSTICCHECK—check working status of sensors and repeaters; CALL FIREDEPARTMENT; CALL TENANT; ALERT OTHERS; Turn ON/OFF POWER; TALK to othersor tenant; SCROLL through screen display, adjust VOLUME, as well as anyother communication or instruction which can be useful in a PMU.

The PMU can also include a transceiver in communication with acontroller. The transceiver can be configured to send and receivecommunications between a monitoring computer and the controller. Thecontroller can be configured to send an electrical signal to a screendisplay or to an audio device in order to alert management to acondition occurring. The controller can be configured to send and/orreceive an electrical signal from a microphone, user input keys, asensor programming interface, a location detector device, or a secondtransceiver for secondary communication channels (e.g., cellular phoneor walkie talkie communication). The controller can also be connected toa computer interface, such as, for example, a USB port, in order tocommunicate via hard wire with a computer.

In one embodiment, the PMU can be configured to receive and sendcommunication with a monitoring computer, repeaters, or sensors. Forinstance, the monitoring computer can send an Alert message indicating aserious condition is occurring. The PMU can display the message in thescreen, or sound an alarm, or cause a pre-recorded message to play. Thedisplay can include any and all relevant information required to assessthe situation such as the Alert type (e.g., FIRE), any relevantinformation about the Alert (e.g., rate of rise of smoke ortemperature), the apartment or unit number, the specific room where thesensor is located, the phone number of the occupants, whether othershave been notified or acknowledged the Alert, as well as any otherinformation relevant in assessing the situation.

In one embodiment, the PMU can be configured to receive and communicatewarning messages. For instance, the monitoring computer can send amessage to the PMU warning that a battery is low in a particular sensor,that a sensor has been tampered with, that a heating unit or airconditioning unit needs maintenance, that a water leak has beendetected, or any other relevant information that can be useful inmaintaining a complex or building.

In one embodiment, the PMU can be configured to receive a diagnosticcheck of the sensors. The diagnostic check can check the battery levelof the sensors and repeaters as well as checking the working status ofeach sensor or repeater or see which ones can need repair orreplacement. The diagnostic check can also check the status of theheating, ventilation, and air conditioning systems. The diagnostic checkcan also be used to monitor any other conditions useful in maintaining abuilding or complex.

In one embodiment, depending on the severity of the alarm, when themonitoring computer communicates a message to the PMU such as an alert,the monitoring computer can wait for an acknowledgement communication tobe sent from the PMU to the monitoring computer. If an acknowledgementis not received, the monitoring computer can attempt to contact otherPMU's or can attempt to contact management through other communicationchannels, for instance, through a telephone communication, a cellular orother wireless communication, a pager, or through the internet. If themonitoring computer is still unable to contact management, themonitoring computer can alert the fire department directly that asituation is occurring at the building or complex. In one embodiment,the monitoring computer can also alert nearby units that a situationnear them is occurring.

If an acknowledgment is received, depending on the severity of thealert, the monitoring computer can also wait for further instructionsfrom the PMU. These instructions can include an OK communicationalerting the monitoring computer that the situation has been taken careof or is simply a false alarm; an instruction to call the firedepartment; an instruction to call the tenants; an instruction to alertothers; or any other useful instruction in dealing with the situation.If further instructions are not received, the monitoring computer canresend the alert, request further instructions from the PMU, attempt tocontact other PMU's or can attempt to contact management through otherchannels, for instance, through a telephone communication, a cellular orother wireless communication, a pager, or through a network. If themonitoring computer is still unable to contact other management andfails to receive further instructions, the monitoring computer can alertthe fire department directly that a situation is occurring at thebuilding or complex.

In one embodiment, the severity or priority of the alarm can be based onthe level of smoke, gas, water, temperature, etc. detected, the amountof time that the sensor has been alerting, the rate of rise of thesubstance detected, the number of sensors alerting to the situation, orany other sensor information useful in assessing the severity orpriority level of the situation.

In one embodiment an adjustable threshold allows the sensor to adjust toambient conditions, aging of components, and other operationalvariations while still providing a relatively sensitive detectioncapability for hazardous conditions. The adjustable threshold sensor canoperate for an extended period of operability without maintenance orrecalibration. In one embodiment, the sensor is self-calibrating andruns through a calibration sequence at startup or at periodic intervals.In one embodiment, the adjustable threshold sensor is used in anintelligent sensor system that includes one or more intelligent sensorunits and a base unit that can communicate with the sensor units. Whenone or more of the sensor units detects an anomalous condition (e.g.,smoke, fire, water, etc.) the sensor unit communicates with the baseunit and provides data regarding the anomalous condition. The base unitcan contact a supervisor or other responsible person by a plurality oftechniques, such as, through a PMU, telephone, pager, cellulartelephone, Internet (and/or local area network), etc. In one embodiment,one or more wireless repeaters are used between the sensor units and thebase unit to extend the range of the system and to allow the base unitto communicate with a larger number of sensors.

In one embodiment, the adjustable-threshold sensor sets a thresholdlevel according to an average value of the sensor reading. In oneembodiment, the average value is a relatively long-term average. In oneembodiment, the average is a time-weighted average wherein recent sensorreadings used in the averaging process are weighted differently thanless recent sensor readings. The average is used to set the thresholdlevel. When the sensor reading rises above the threshold level, thesensor indicates an alarm condition. In one embodiment, the sensorindicates an alarm condition when the sensor reading rises above thethreshold value for a specified period of time. In one embodiment, thesensor indicates an alarm condition when a statistical number of sensorreadings (e.g., 3 of 2, 5 of 3, 10 of 7, etc.) are above the thresholdlevel. In one embodiment, the sensor indicates various levels of alarm(e.g., notice, alert, alarm) based on how far above the threshold thesensor reading has risen and/or how rapidly the sensor reading hasrisen.

In one embodiment, the sensor system includes a number of sensor unitslocated throughout a building that sense conditions and report anomalousresults back to a central reporting station. The sensor units measureconditions that might indicate a fire, water leak, etc. The sensor unitsreport the measured data to the base unit whenever the sensor unitdetermines that the measured data is sufficiently anomalous to bereported. The base unit can notify a responsible person such as, forexample, a building manager, building owner, private security service,etc. In one embodiment, the sensor units do not send an alarm signal tothe central location. Rather, the sensors send quantitative measureddata (e.g., smoke density, temperature rate of rise, etc.) to thecentral reporting station.

In one embodiment, the sensor system includes a battery-operated sensorunit that detects a condition, such as, for example, smoke, temperature,humidity, moisture, water, water temperature, carbon monoxide, naturalgas, propane gas, other flammable gases, radon, poison gasses, etc. Thesensor unit is placed in a building, apartment, office, residence, etc.In order to conserve battery power, the sensor is normally placed in alow-power mode. In one embodiment, while in the low-power mode, thesensor unit takes regular sensor readings, adjusts the threshold level,and evaluates the readings to determine if an anomalous conditionexists. If an anomalous condition is detected, then the sensor unit“wakes up” and begins communicating with the base unit or with arepeater. At programmed intervals, the sensor also “wakes up” and sendsstatus information to the base unit (or repeater) and then listens forcommands for a period of time.

In one embodiment, the sensor unit is bi-directional and configured toreceive instructions from the central reporting station (or repeater).Thus, for example, the central reporting station can instruct the sensorto: perform additional measurements; go to a standby mode; wake up;report battery status; change wake-up interval; run self-diagnostics andreport results; report its threshold level, change its threshold level,change its threshold calculation equation, change its alarm calculationequation, etc. In one embodiment, the sensor unit also includes a tamperswitch. When tampering with the sensor is detected, the sensor reportssuch tampering to the base unit. In one embodiment, the sensor reportsits general health and status to the central reporting station on aregular basis (e.g., results of self-diagnostics, battery health, etc.).

In one embodiment, the sensor unit provides two wake-up modes, a firstwake-up mode for taking measurements (and reporting such measurements ifdeemed necessary), and a second wake-up mode for listening for commandsfrom the central reporting station. The two wake-up modes, orcombinations thereof, can occur at different intervals.

In one embodiment, the sensor units use spread-spectrum techniques tocommunicate with the base unit and/or the repeater units. In oneembodiment, the sensor units use frequency-hopping spread-spectrum. Inone embodiment, each sensor unit has an Identification code (ID) and thesensor units attaches its ID to outgoing communication packets. In oneembodiment, when receiving wireless data, each sensor unit ignores datathat is addressed to other sensor units.

The repeater unit is configured to relay communications traffic betweena number of sensor units and the base unit. The repeater units typicallyoperate in an environment with several other repeater units and thus,each repeater unit contains a database (e.g., a lookup table) of sensorIDs. During normal operation, the repeater only communicates withdesignated wireless sensor units whose IDs appear in the repeater'sdatabase. In one embodiment, the repeater is battery-operated andconserves power by maintaining an internal schedule of when it'sdesignated sensors are expected to transmit and going to a low-powermode when none of its designated sensor units is scheduled to transmit.In one embodiment, the repeater uses spread-spectrum to communicate withthe base unit and the sensor units. In one embodiment, the repeater usesfrequency-hopping spread-spectrum to communicate with the base unit andthe sensor units. In one embodiment, each repeater unit has an ID andthe repeater unit attaches its ID to outgoing communication packets thatoriginate in the repeater unit. In one embodiment, each repeater unitignores data that is addressed to other repeater units or to sensorunits not serviced by the repeater.

In one embodiment, the repeater is configured to provide bi-directionalcommunication between one or more sensors and a base unit. In oneembodiment, the repeater is configured to receive instructions from thecentral reporting station (or repeater). Thus, for example, the centralreporting station can instruct the repeater to: send commands to one ormore sensors; go to standby mode; “wake up”; report battery status;change wake-up interval; run self-diagnostics and report results; etc.

The base unit is configured to receive measured sensor data from anumber of sensor units. In one embodiment, the sensor information isrelayed through the repeater units. The base unit also sends commands tothe repeater units and/or sensor units. In one embodiment, the base unitincludes a diskless PC that runs off of a CD-ROM, flash memory, DVD, orother read-only device, etc. When the base unit receives data from awireless sensor indicating that there can be an emergency condition(e.g., a fire or excess smoke, temperature, water, flammable gas, etc.)the base unit will attempt to notify a responsible party (e.g., abuilding manager) by several communication channels (e.g., telephone,Internet, pager, cell phone, etc.). In one embodiment, the base unitsends instructions to place the wireless sensor in an alert mode(inhibiting the wireless sensor's low-power mode). In one embodiment,the base unit sends instructions to activate one or more additionalsensors near the first sensor.

In one embodiment, the base unit maintains a database of the health,battery status, signal strength, and current operating status of all ofthe sensor units and repeater units in the wireless sensor system. Inone embodiment, the base unit automatically performs routine maintenanceby sending commands to each sensor to run a self-diagnostic and reportthe results. The base unit collects such diagnostic results. In oneembodiment, the base unit sends instructions to each sensor telling thesensor how long to wait between “wakeup” intervals. In one embodiment,the base unit schedules different wakeup intervals to different sensorsbased on the sensor's health, battery health, location, etc. In oneembodiment, the base unit sends instructions to repeaters to routesensor information around a failed repeater.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows sensor system that includes a plurality of sensor unitsthat communicate with a base unit through a number of repeater units andalso communicates with a PMU.

FIG. 2 is a block diagram of a sensor unit.

FIG. 3 is a block diagram of a repeater unit.

FIG. 4 is a block diagram of the base unit.

FIG. 5 shows a network communication packet used by the sensor units,repeater units, base unit, and PMU.

FIG. 6 is a flowchart showing operation of a sensor unit that providesrelatively continuous monitoring.

FIG. 7 is a flowchart showing operation of a sensor unit that providesperiodic monitoring.

FIG. 8 shows how the sensor system can be used to detect water leaks.

FIG. 9 shows an example of one embodiment of a PMU.

FIG. 10 shows a graphical representation of an alert of one embodiment.

FIG. 11 shows a graphical representation of a warning of one embodiment.

FIG. 12 shows a graphical representation of a diagnostic check of oneembodiment.

FIG. 13 is a block diagram of the PMU.

FIG. 14 is a flowchart showing the operation of a sensor system incommunication with a PMU.

FIG. 15 is a graphical representation of a priority/response chart.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a sensor system 100 that includes a plurality of sensorunits 102-106 that communicate with a base unit 112 through a number ofrepeater units 110-111. The sensor units 102-106 are located throughouta building 101. Sensor units 102-104 communicate with the repeater 110.Sensor units 105-106 communicate with the repeater 111. The repeaters110-111 communicate with the base unit 112. The base unit 112communicates with a monitoring computer system 113 through a computernetwork connection such as, for example, Ethernet, wireless Ethernet,firewire port, Universal Serial Bus (USB) port, Bluetooth, etc. Thecomputer system 113 contacts a building manager, maintenance service,alarm service, or other responsible personnel 120 using one or more ofseveral communication systems such as, for example, PMU 125, telephone121, pager 122, cellular telephone 123 (e.g., direct contact, voicemail,text, etc.), and/or through the Internet and/or local area network 124(e.g., through email, instant messaging, network communications, etc.).In one embodiment, multiple base units 112 are provided to themonitoring computer 113. In one embodiment, the monitoring computer 113is provided to more than one computer monitors, thus, allowing more datato be displayed than can conveniently be displayed on a single monitor.In one embodiment, the monitoring computer 113 is provided to multiplemonitors located in different locations, thus allowing the data from themonitoring computer 113 to be displayed in multiple locations.

The sensor units 102-106 include sensors to measure conditions, such as,for example, smoke, temperature, moisture, water, water temperature,humidity, carbon monoxide, natural gas, propane gas, security alarms,intrusion alarms (e.g., open doors, broken windows, open windows, andthe like), other flammable gases, radon, poison gasses, etc. Differentsensor units can be configured with different sensors or withcombinations of sensors. Thus, for example, in one installation thesensor units 102 and 104 could be configured with smoke and/ortemperature sensors while the sensor unit 103 could be configured with ahumidity sensor.

The discussion that follows generally refers to the sensor unit 102 asan example of a sensor unit, with the understanding that the descriptionof the sensor unit 102 can be applied to many sensor units. Similarly,the discussion generally refers to the repeater 110 by way of example,and not limitation. It will also be understood by one of ordinary skillin the art that repeaters are useful for extending the range of thesensor units 102-106 but are not required in all embodiments. Thus, forexample, in one embodiment, one or more of the sensor units 102-106 cancommunicate directly with the base unit 112 without going through arepeater. It will also be understood by one of ordinary skill in the artthat FIG. 1 shows only five sensor units (102-106) and two repeaterunits (110-111) for purposes of illustration and not by way oflimitation. An installation in a large apartment building or complexwould typically involve many sensor units and repeater units. Moreover,one of ordinary skill in the art will recognize that one repeater unitcan service relatively many sensor units. In one embodiment, the sensorunits 102 can communicate directly with the base unit 112 without goingthrough a repeater 111.

When the sensor unit 102 detects an anomalous condition (e.g., smoke,fire, water, etc.) the sensor unit communicates with the appropriaterepeater unit 110 and provides data regarding the anomalous condition.The repeater unit 110 forwards the data to the base unit 112, and thebase unit 112 forwards the information to the computer 113. The computer113 evaluates the data and takes appropriate action. If the computer 113determines that the condition is an emergency (e.g., fire, smoke, largequantities of water), then the computer 113 contacts the appropriatepersonnel 120. If the computer 113 determines that a the situationwarrants reporting, but is not an emergency, then the computer 113 canlog the data for later reporting, or can send a warning message to thePMU 125. In this way, the sensor system 100 can monitor the conditionsin and around the building 101.

In one embodiment, the sensor unit 102 has an internal power source(e.g., battery, solar cell, fuel cell, etc.). In order to conservepower, the sensor unit 102 is normally placed in a low-power mode. Inone embodiment, using sensors that require relatively little power,while in the low-power mode the sensor unit 102 takes regular sensorreadings and evaluates the readings to determine if an anomalouscondition exists. In one embodiment, using sensors that requirerelatively more power, while in the low-power mode, the sensor unit 102takes and evaluates sensor readings at periodic intervals. If ananomalous condition is detected, then the sensor unit 102 “wakes up” andbegins communicating with the base unit 112 through the repeater 110. Atprogrammed intervals, the sensor unit 102 also “wakes up” and sendsstatus information (e.g., power levels, self diagnostic information,etc.) to the base unit (or repeater) and then listens for commands for aperiod of time. In one embodiment, the sensor unit 102 also includes atamper detector. When tampering with the sensor unit 102 is detected,the sensor unit 102 reports such tampering to the base unit 112.

In one embodiment, the sensor unit 102 provides bi-directionalcommunication and is configured to receive data and/or instructions fromthe base unit 112. Thus, for example, the base unit 112 can instruct thesensor unit 102 to perform additional measurements, to go to a standbymode, to wake up, to report battery status, to change wake-up interval,to run self-diagnostics and report results, etc. In one embodiment, thesensor unit 102 reports its general health and status on a regular basis(e.g., results of self-diagnostics, battery health, etc.)

In one embodiment, the sensor unit 102 provides two wake-up modes, afirst wake-up mode for taking measurements (and reporting suchmeasurements if deemed necessary), and a second wake-up mode forlistening for commands from the central reporting station. The twowake-up modes, or combinations thereof, can occur at differentintervals.

In one embodiment, the sensor unit 102 use spread-spectrum techniques tocommunicate with the repeater unit 110. In one embodiment, the sensorunit 102 use frequency-hopping spread-spectrum. In one embodiment, thesensor unit 102 has an address or identification (ID) code thatdistinguishes the sensor unit 102 from the other sensor units. Thesensor unit 102 attaches its ID to outgoing communication packets sothat transmissions from the sensor unit 102 can be identified by therepeater 110. The repeater 110 attaches the ID of the sensor unit 102 todata and/or instructions that are transmitted to the sensor unit 102. Inone embodiment, the sensor unit 102 ignores data and/or instructionsthat are addressed to other sensor units.

In one embodiment, the sensor unit 102 includes a reset function. In oneembodiment, the reset function is activated by the reset switch 208. Inone embodiment, the reset function is active for a prescribed intervalof time. During the reset interval, the transceiver 203 is in areceiving mode and can receive the identification code from an externalprogrammer. In one embodiment, the external programmer wirelesslytransmits a desired identification code. In one embodiment, theidentification code is programmed by an external programmer that isconnected to the sensor unit 102 through an electrical connector. In oneembodiment, the electrical connection to the sensor unit 102 is providedby sending modulated control signals (power line carrier signals)through a connector used to connect the power source 206. In oneembodiment, the external programmer provides power and control signals.In one embodiment, the external programmer also programs the type ofsensor(s) installed in the sensor unit. In one embodiment, theidentification code includes an area code (e.g., apartment number, zonenumber, floor number, etc.) and a unit number (e.g., unit 1, 2, 3,etc.). In one embodiment, the PMU is used to program the sensor unit102.

In one embodiment, the sensor communicates with the repeater on the 900MHz band. This band provides good transmission through walls and otherobstacles normally found in and around a building structure. In oneembodiment, the sensor communicates with the repeater on bands aboveand/or below the 900 MHz band. In one embodiment, the sensor, repeater,and/or base unit listens to a radio frequency channel beforetransmitting on that channel or before beginning transmission. If thechannel is in use, (e.g., by another device such as another repeater, acordless telephone, etc.) then the sensor, repeater, and/or base unitchanges to a different channel. In one embodiment, the sensor, repeater,and/or base unit coordinate frequency hopping by listening to radiofrequency channels for interference and using an algorithm to select anext channel for transmission that avoids the interference. Thus, forexample, in one embodiment, if a sensor senses a dangerous condition andgoes into a continuous transmission mode, the sensor will test (e.g.,listen to) the channel before transmission to avoid channels that areblocked, in use, or jammed. In one embodiment, the sensor continues totransmit data until it receives an acknowledgement from the base unitthat the message has been received. In one embodiment, the sensortransmits data having a normal priority (e.g., status information) anddoes not look for an acknowledgement, and the sensor transmits datahaving elevated priority (e.g., excess smoke, temperature, etc.) untilan acknowledgement is received.

The repeater unit 10 is configured to relay communications trafficbetween the sensor 102 (and similarly, the sensor units 103-104) and thebase unit 112. The repeater unit 110 typically operates in anenvironment with several other repeater units (such as the repeater unit111 in FIG. 1) and thus, the repeater unit 110 contains a database(e.g., a lookup table) of sensor unit IDs. In FIG. 1, the repeater 110has database entries for the Ids of the sensors 102-104, and thus, thesensor 110 will only communicate with sensor units 102-104. In oneembodiment, the repeater 110 has an internal power source (e.g.,battery, solar cell, fuel cell, etc.) and conserves power by maintainingan internal schedule of when the sensor units 102-104 are expected totransmit. In one embodiment, the repeater unit 110 goes to a low-powermode when none of its designated sensor units is scheduled to transmit.In one embodiment, the repeater 110 uses spread-spectrum techniques tocommunicate with the base unit 112 and with the sensor units 102-104. Inone embodiment, the repeater 110 uses frequency-hopping spread-spectrumto communicate with the base unit 112 and the sensor units 102-104. Inone embodiment, the repeater unit 110 has an address or identification(ID) code and the repeater unit 110 attaches its address to outgoingcommunication packets that originate in the repeater (that is, packetsthat are not being forwarded). In one embodiment, the repeater unit 110ignores data and/or instructions that are addressed to other repeaterunits or to sensor units not serviced by the repeater 110.

In one embodiment, the base unit 112 communicates with the sensor unit102 by transmitting a communication packet addressed to the sensor unit102. The repeaters 110 and 111 both receive the communication packetaddressed to the sensor unit 102. The repeater unit 111 ignores thecommunication packet addressed to the sensor unit 102. The repeater unit110 transmits the communication packet addressed to the sensor unit 102to the sensor unit 102. In one embodiment, the sensor unit 102, therepeater unit 110, and the base unit 112 communicate usingFrequency-Hopping Spread Spectrum (FHSS), also known as channel-hopping.

Frequency-hopping wireless systems offer the advantage of avoiding otherinterfering signals and avoiding collisions. Moreover, there areregulatory advantages given to systems that do not transmit continuouslyat one frequency. Channel-hopping transmitters change frequencies aftera period of continuous transmission, or when interference isencountered. These systems can have higher transmit power and relaxedlimitations on in-band spurs. FCC regulations limit transmission time onone channel to 400 milliseconds (averaged over 10-20 seconds dependingon channel bandwidth) before the transmitter must change frequency.There is a minimum frequency step when changing channels to resumetransmission. If there are 25 to 49 frequency channels, regulationsallow effective radiated power of 24 dBm, spurs must be −20 dBc, andharmonics must be −41.2 dBc. With 50 or more channels, regulations alloweffective radiated power to be up to 30 dBm.

In one embodiment, the sensor unit 102, the repeater unit 110, and thebase unit 112 communicate using FHSS wherein the frequency hopping ofthe sensor unit 102, the repeater unit 110, and the base unit 112 arenot synchronized such that at any given moment, the sensor unit 102 andthe repeater unit 110 are on different channels. In such a system, thebase unit 112 communicates with the sensor unit 102 using the hopfrequencies synchronized to the repeater unit 110 rather than the sensorunit 102. The repeater unit 110 then forwards the data to the sensorunit using hop frequencies synchronized to the sensor unit 102. Such asystem largely avoids collisions between the transmissions by the baseunit 112, the PMU 125, and the repeater unit 110.

In one embodiment, the sensor units 102-106 all use FHSS and the sensorunits 102-106 are not synchronized. Thus, at any given moment, it isunlikely that any two or more of the sensor units 102-106 will transmiton the same frequency. In this manner, collisions are largely avoided.In one embodiment, collisions are not detected but are tolerated by thesystem 100. If a collisions does occur, data lost due to the collisionis effectively re-transmitted the next time the sensor units transmitsensor data. When the sensor units 102-106 and repeater units 110-111operate in asynchronous mode, then a second collision is highly unlikelybecause the units causing the collisions have hopped to differentchannels. In one embodiment, the sensor units 102-106, repeater units110-111, PMU 125, and the base unit 112 use the same hop rate. In oneembodiment, the sensor units 102-106, repeater units 110-111, PMU 125,and the base unit 112 use the same pseudo-random algorithm to controlchannel hopping, but with different starting seeds. In one embodiment,the starting seed for the hop algorithm is calculated from the ID of thesensor units 102-106, repeater units 110-111, PMU 125, or the base unit112.

In an alternative embodiment, the base unit communicates with the sensorunit 102 by sending a communication packet addressed to the repeaterunit 110, where the packet sent to the repeater unit 110 includes theaddress of the sensor unit 102. The repeater unit 102 extracts theaddress of the sensor unit 102 from the packet and creates and transmitsa packet addressed to the sensor unit 102.

In one embodiment, the repeater unit 110 is configured to providebi-directional communication between its sensors and the base unit 112.In one embodiment, the repeater 110 is configured to receiveinstructions from the base unit 112. Thus, for example, the base unit112 can instruct the repeater to: send commands to one or more sensors;go to standby mode; “wake up”; report battery status; change wake-upinterval; run self-diagnostics and report results; etc.

The base unit 112 is configured to receive measured sensor data from anumber of sensor units either directly, or through the repeaters110-111. The base unit 112 also sends commands to the repeater units110-111 and/or to the sensor units 102-106. In one embodiment, the baseunit 112 communicates with a diskless computer 113 that runs off of aCD-ROM. When the base unit 112 receives data from a sensor unit 102-106indicating that there can be an emergency condition (e.g., a fire orexcess smoke, temperature, water, etc.) the computer 113 will attempt tonotify the responsible party 120.

In one embodiment, the computer 112 maintains a database of the health,power status (e.g., battery charge), and current operating status of allof the sensor units 102-106 and the repeater units 110-111. In oneembodiment, the computer 113 automatically performs routine maintenanceby sending commands to each sensor unit 102-106 to run a self-diagnosticand report the results. The computer 113 collects and logs suchdiagnostic results. In one embodiment, the computer 113 sendsinstructions to each sensor unit 102-106 telling the sensor how long towait between “wakeup” intervals. In one embodiment, the computer 113schedules different wakeup intervals to different sensor unit 102-106based on the sensor unit's health, power status, location, etc. In oneembodiment, the computer 113 schedules different wakeup intervals todifferent sensor unit 102-106 based on the type of data and urgency ofthe data collected by the sensor unit (e.g., sensor units that havesmoke and/or temperature sensors produce data that should be checkedrelatively more often than sensor units that have humidity or moisturesensors). In one embodiment, the base unit sends instructions torepeaters to route sensor information around a failed repeater.

In one embodiment, the computer 113 produces a display that tellsmaintenance personnel which sensor units 102-106 need repair ormaintenance. In one embodiment, the computer 113 maintains a listshowing the status and/or location of each sensor according to the ID ofeach sensor.

In one embodiment, the sensor units 102-106 and /or the repeater units110-111 measure the signal strength of the wireless signals received(e.g., the sensor unit 102 measures the signal strength of the signalsreceived from the repeater unit 110, the repeater unit 110 measures thesignal strength received from the sensor unit 102 and/or the base unit112). The sensor units 102-106 and /or the repeater units 110-111 reportsuch signal strength measurement back to the computer 113. The computer113 evaluates the signal strength measurements to ascertain the healthand robustness of the sensor system 100. In one embodiment, the computer113 uses the signal strength information to re-route wirelesscommunications traffic in the sensor system 100. Thus, for example, ifthe repeater unit 110 goes offline or is having difficulty communicatingwith the sensor unit 102, the computer 113 can send instructions to therepeater unit 111 to add the ID of the sensor unit 102 to the databaseof the repeater unit 111 (and similarly, send instructions to therepeater unit 110 to remove the ID of the sensor unit 102), therebyrouting the traffic for the sensor unit 102 through the router unit 111instead of the router unit 110.

In one embodiment, a PMU 125 communicates with the sensor system 100. Itwill be understood by a person of skill in the art that the PMU 125 cancommunicate with various sensor systems. The description that follows ofthe PMU 125 is meant by way of explanation and not by way of limitation.In one embodiment, the monitoring computer 113 sends any requiredcommunications to the PMU 125 which conveys the information tomanagement 120. The monitoring computer 113 can send the communicationthrough base unit 112, or through any other communication channels.Optionally, the sensor units and repeater units can communicate directlywith the PMU 1.

In one embodiment, one or more PMUs can communicate with the monitoringcomputer 113 at the same time. PMU 125 can be configured individually sothat only certain PMUs can communicate with the system, or PMU 125 canbe configured to communicate with multiple systems. PMU 125 can also beconfigured to identify the user. Different authorization levels can begiven to different users to allow different access levels to the sensorsystem.

In one embodiment, the PMU 125 uses spread-spectrum techniques tocommunicate with the sensor units, repeater units, or base unit 112. Inone embodiment, the PMU 125 uses frequency-hopping spread-spectrum. Inone embodiment, the PMU 125 has an address or identification (ID) codethat distinguishes the PMU 125 from the other PMUs. The PMU 125 canattach its ID to outgoing communication packets so that transmissionsfrom the PMU 125 can be identified by the base 112, sensor units, orrepeater units.

In one embodiment, the sensor units, the repeater units, the base unit,and the PMU 125 communicate using FHSS wherein the frequency hopping ofthe sensor units, the repeater units, the base unit, and the PMU 125 arenot synchronized such that at any given moment, the sensor units and therepeater units are on different channels. In such a system, the baseunit 112 or PMU 125 communicates with the sensor units using the hopfrequencies synchronized to the repeater units rather than the sensorunits. The repeater units then forward the data to the sensor unitsusing hop frequencies synchronized to the sensor units. Such a systemlargely avoids collisions between the transmissions by the base unit112, the PMU 125, and the repeater units.

In one embodiment, the sensor units communicate with the repeater units,base 112, or PMU 125 on the 900 MHz band. This band provides goodtransmission through walls and other obstacles normally found in andaround a building structure. In one embodiment, the sensor unitscommunicate with the repeater units, base 112, or PMU 125 on bands aboveand/or below the 900 MHz band. In one embodiment, the sensor units,repeater units, base unit 112, and/or PMU 125 listen to a radiofrequency channel before transmitting on that channel or beforebeginning transmission. If the channel is in use, (e.g., by anotherdevice such as another repeater unit, a cordless telephone, etc.) thenthe sensor units, repeater units, base unit 112, and/or PMU 125 changeto a different channel. In one embodiment, the sensor units, repeaterunits, base unit 112 and/or PMU 125 coordinate frequency hopping bylistening to radio frequency channels for interference and using analgorithm to select a next channel for transmission that avoids theinterference. Thus, for example, in one embodiment, if a PMU 125 isinstructed to send a communication, the PMU 125 will test (e.g., listento) the channel before transmission to avoid channels that are blocked,in use, or jammed.

FIG. 2 is a block diagram of the sensor unit 102. In the sensor unit102, one or more sensors 201 and a transceiver 203 are provided to acontroller 202. The controller 202 typically provides power, data, andcontrol information to the sensor(s) 201 and the transceiver 202. Apower source 206 is provided to the controller 202. An optional tampersensor 205 is also provided to the controller 202. A reset device (e.g.,a switch) 208 is proved to the controller 202. In one embodiment, anoptional audio output device 209 is provided. In one embodiment, thesensor 201 is configured as a plug-in module that can be replacedrelatively easily. In one embodiment, a temperature sensor 220 isprovided to the controller 202. In one embodiment, the temperaturesensor 220 is configured to measure ambient temperature.

In one embodiment, the transceiver 203 is based on a TRF 6901transceiver chip from Texas Instruments, Inc. In one embodiment, thecontroller 202 is a conventional programmable microcontroller. In oneembodiment, the controller 202 is based on a Field Programmable GateArray (FPGA), such as, for example, provided by Xilinx Corp. In oneembodiment, the sensor 201 includes an optoelectric smoke sensor with asmoke chamber. In one embodiment, the sensor 201 includes a thermistor.In one embodiment, the sensor 201 includes a humidity sensor. In oneembodiment, the sensor 201 includes a sensor, such as, for example, awater level sensor, a water temperature sensor, a carbon monoxidesensor, a moisture sensor, a water flow sensor, natural gas sensor,propane sensor, etc.

The controller 202 receives sensor data from the sensor(s) 201. Somesensors 201 produce digital data. However, for many types of sensors201, the sensor data is analog data. Analog sensor data is converted todigital format by the controller 202. In one embodiment, the controllerevaluates the data received from the sensor(s) 201 and determineswhether the data is to be transmitted to the base unit 112. The sensorunit 102 generally conserves power by not transmitting data that fallswithin a normal range. In one embodiment, the controller 202 evaluatesthe sensor data by comparing the data value to a threshold value (e.g.,a high threshold, a low threshold, or a high-low threshold). If the datais outside the threshold (e.g., above a high threshold, below a lowthreshold, outside an inner range threshold, or inside an outer rangethreshold), then the data is deemed to be anomalous and is transmittedto the base unit 112. In one embodiment, the data threshold isprogrammed into the controller 202. In one embodiment, the datathreshold is programmed by the base unit 112 by sending instructions tothe controller 202. In one embodiment, the controller 202 obtains sensordata and transmits the data when commanded by the computer 113.

In one embodiment, the tamper sensor 205 is configured as a switch thatdetects removal of/or tampering with the sensor unit 102.

FIG. 3 is a block diagram of the repeater unit 110. In the repeater unit110, a first transceiver 302 and a second transceiver 304 are providedto a controller 303. The controller 303 typically provides power, data,and control information to the transceivers 302, 304. A power source 306is provided to the controller 303. An optional tamper sensor (not shown)is also provided to the controller 303.

When relaying sensor data to the base unit 112, the controller 303receives data from the first transceiver 302 and provides the data tothe second transceiver 304. When relaying instructions from the baseunit 112 to a sensor unit, the controller 303 receives data from thesecond transceiver 304 and provides the data to the first transceiver302. In one embodiment, the controller 303 conserves power bypowering-down the transceivers 302, 304 during periods when thecontroller 303 is not expecting data. The controller 303 also monitorsthe power source 306 and provides status information, such as, forexample, self-diagnostic information and/or information about the healthof the power source 306, to the base unit 112. In one embodiment, thecontroller 303 sends status information to the base unit 112 at regularintervals. In one embodiment, the controller 303 sends statusinformation to the base unit 112 when requested by the base unit 112. Inone embodiment, the controller 303 sends status information to the baseunit 112 when a fault condition (e.g., battery low) is detected.

In one embodiment, the controller 303 includes a table or list ofidentification codes for wireless sensor units 102. The repeater 303forwards packets received from, or sent to, sensor units 102 in thelist. In one embodiment, the repeater 110 receives entries for the listof sensor units from the computer 113. In one embodiment, the controller303 determines when a transmission is expected from the sensor units 102in the table of sensor units and places the repeater 110 (e.g., thetransceivers 302, 304) in a low-power mode when no transmissions areexpected from the transceivers on the list. In one embodiment, thecontroller 303 recalculates the times for low-power operation when acommand to change reporting interval is forwarded to one of the sensorunits 102 in the list (table) of sensor units or when a new sensor unitis added to the list (table) of sensor units.

FIG. 4 is a block diagram of the base unit 112. In the base unit 112, atransceiver 402 and a computer interface 404 are provided to acontroller 403. The controller 303 typically provides data and controlinformation to the transceivers 402 and to the interface. The interface404 is provided to a port on the monitoring computer 113. The interface404 can be a standard computer data interface, such as, for example,Ethernet, wireless Ethernet, firewire port, Universal Serial Bus (USB)port, Bluetooth, etc.

FIG. 5 shows one embodiment of a communication packet 500 used by thesensor units, repeater units, base unit, and PMU. The packet 500includes a preamble portion 501, an address (or ID) portion 502, a datapayload portion 503, and an integrity portion 504. In one embodiment,the integrity portion 504 includes a checksum. In one embodiment, thesensor units 102-106, the repeater units 110-111, and the base unit 112communicate using packets such as the packet 500. In one embodiment, thepackets 500 are transmitted using FHSS.

In one embodiment, the data packets that travel between the sensor unit102, the repeater unit 111, the base unit 112, and the PMU 125 areencrypted. In one embodiment, the data packets that travel between thesensor unit 102, the repeater unit 111, the base unit 112, and the PMU125 are encrypted and an authentication code is provided in the datapacket so that the sensor unit 102, the repeater unit, and/or the baseunit 112 can verify the authenticity of the packet.

In one embodiment the address portion 502 includes a first code and asecond code. In one embodiment, the repeater 111 only examines the firstcode to determine if the packet should be forwarded. Thus, for example,the first code can be interpreted as a building (or building complex)code and the second code interpreted as a subcode (e.g., an apartmentcode, area code, etc.). A repeater that uses the first code forforwarding, thus, forwards packets having a specified first code (e.g.,corresponding to the repeater's building or building complex). Thus,alleviates the need to program a list of sensor units 102 into arepeater, since a group of sensors in a building will typically all havethe same first code but different second codes. A repeater soconfigured, only needs to know the first code to forward packets for anyrepeater in the building or building complex. This does, however, raisethe possibility that two repeaters in the same building could try toforward packets for the same sensor unit 102. In one embodiment, eachrepeater waits for a programmed delay period before forwarding a packet.Thus, reducing the chance of packet collisions at the base unit (in thecase of sensor unit to base unit packets) and reducing the chance ofpacket collisions at the sensor unit (in the case of base unit to sensorunit packets). In one embodiment, a delay period is programmed into eachrepeater. In one embodiment, delay periods are pre-programmed onto therepeater units at the factory or during installation. In one embodiment,a delay period is programmed into each repeater by the base unit 112. Inone embodiment, a repeater randomly chooses a delay period. In oneembodiment, a repeater randomly chooses a delay period for eachforwarded packet. In one embodiment, the first code is at least 6digits. In one embodiment, the second code is at least 5 digits.

In one embodiment, the first code and the second code are programmedinto each sensor unit at the factory. In one embodiment, the first codeand the second code are programmed when the sensor unit is installed. Inone embodiment, the base unit 112 can re-program the first code and/orthe second code in a sensor unit.

In one embodiment, collisions are further avoided by configuring eachrepeater unit 111 to begin transmission on a different frequencychannel. Thus, if two repeaters attempt to begin transmission at thesame time, the repeaters will not interfere with each other because thetransmissions will begin on different channels (frequencies).

FIG. 6 is a flowchart showing one embodiment of the operation of thesensor unit 102 wherein relatively continuous monitoring is provided. InFIG. 6, a power up block 601 is followed by an initialization block 602.After initialization, the sensor unit 102 checks for a fault condition(e.g., activation of the tamper sensor, low battery, internal fault,etc.) in a block 603. A decision block 604 checks the fault status. If afault has occurred, then the process advances to a block 605 were thefault information is transmitted to the repeater 110 (after which, theprocess advances to a block 612); otherwise, the process advances to ablock 606. In the block 606, the sensor unit 102 takes a sensor readingfrom the sensor(s) 201. The sensor data is subsequently evaluated in ablock 607. If the sensor data is abnormal, then the process advances toa transmit block 609 where the sensor data is transmitted to therepeater 110 (after which, the process advances to a block 612);otherwise, the process advances to a timeout decision block 610. If thetimeout period has not elapsed, then the process returns to thefault-check block 603; otherwise, the process advances to a transmitstatus block 611 where normal status information is transmitted to therepeater 110. In one embodiment, the normal status informationtransmitted is analogous to a simple “ping” which indicates that thesensor unit 102 is functioning normally. After the block 611, theprocess proceeds to a block 612 where the sensor unit 102 momentarilylistens for instructions from the monitor computer 113. If aninstruction is received, then the sensor unit 102 performs theinstructions, otherwise, the process returns to the status check block603. In one embodiment, transceiver 203 is normally powered down. Thecontroller 202 powers up the transceiver 203 during execution of theblocks 605, 609, 611, and 612. The monitoring computer 113 can sendinstructions to the sensor unit 102 to change the parameters used toevaluate data used in block 607, the listen period used in block 612,etc.

Relatively continuous monitoring, such as shown in FIG. 6, isappropriate for sensor units that sense relatively high-priority data(e.g., smoke, fire, carbon monoxide, flammable gas, etc.). By contrast,periodic monitoring can be used for sensors that sense relatively lowerpriority data (e.g., humidity, moisture, water usage, etc.). FIG. 7 is aflowchart showing one embodiment of operation of the sensor unit 102wherein periodic monitoring is provided. In FIG. 7, a power up block 701is followed by an initialization block 702. After initialization, thesensor unit 102 enters a low-power sleep mode. If a fault occurs duringthe sleep mode (e.g., the tamper sensor is activated), then the processenters a wake-up block 704 followed by a transmit fault block 705. If nofault occurs during the sleep period, then when the specified sleepperiod has expired, the process enters a block 706 where the sensor unit102 takes a sensor reading from the sensor(s) 201. The sensor data issubsequently sent to the monitoring computer 113 in a report block 707.After reporting, the sensor unit 102 enters a listen block 708 where thesensor unit 102 listens for a relatively short period of time forinstructions from monitoring computer 708. If an instruction isreceived, then the sensor unit 102 performs the instructions, otherwise,the process returns to the sleep block 703. In one embodiment, thesensor 201 and transceiver 203 are normally powered down. The controller202 powers up the sensor 201 during execution of the block 706. Thecontroller 202 powers up the transceiver during execution of the blocks705, 707, and 708. The monitoring computer 113 can send instructions tothe sensor unit 102 to change the sleep period used in block 703, thelisten period used in block 708, etc.

In one embodiment, the sensor unit transmits sensor data until ahandshaking-type acknowledgement is received. Thus, rather than sleep ofno instructions or acknowledgements are received after transmission(e.g., after the decision block 613 or 709) the sensor unit 102retransmits its data and waits for an acknowledgement. The sensor unit102 continues to transmit data and wait for an acknowledgement until anacknowledgement is received. In one embodiment, the sensor unit acceptsan acknowledgement from a repeater unit 111 and it then becomes theresponsibility of the repeater unit 111 to make sure that the data isforwarded to the base unit 112. In one embodiment, the repeater unit 111does not generate the acknowledgement, but rather forwards anacknowledgement from the base unit 112 to the sensor unit 102. Thetwo-way communication ability of the sensor unit 102 provides thecapability for the base unit 112 to control the operation of the sensorunit 102 and also provides the capability for robust handshaking-typecommunication between the sensor unit 102 and the base unit 112.

Regardless of the normal operating mode of the sensor unit 102 (e.g.,using the Flowcharts of FIGS. 6, 7, or other modes) in one embodiment,the monitoring computer 113 can instruct the sensor unit 102 to operatein a relatively continuous mode where the sensor repeatedly takes sensorreadings and transmits the readings to the monitoring computer 113. Sucha mode would can be used, for example, when the sensor unit 102 (or anearby sensor unit) has detected a potentially dangerous condition(e.g., smoke, rapid temperature rise, etc.)

FIG. 8 shows the sensor system used to detect water leaks. In oneembodiment, the sensor unit 102 includes a water level sensor and 803and/or a water temperature sensor 804. The water level sensor 803 and/orwater temperature sensor 804 are place, for example, in a trayunderneath a water heater 801 in order to detect leaks from the waterheater 801 and thereby prevent water damage from a leaking water heater.In one embodiment, a temperature sensor is also provide to measuretemperature near the water heater. The water level sensor can also beplaced under a sink, in a floor sump, etc. In one embodiment, theseverity of a leak is ascertained by the sensor unit 102 (or themonitoring computer 113) by measuring the rate of rise in the waterlevel. When placed near the hot water tank 801, the severity of a leakcan also be ascertained at least in part by measuring the temperature ofthe water. In one embodiment, a first water flow sensor is placed in aninput water line for the hot water tank 801 and a second water flowsensor is placed in an output water line for the hot water tank. Leaksin the tank can be detected by observing a difference between the waterflowing through the two sensors.

In one embodiment, a remote shutoff valve 810 is provided, so that themonitoring system 100 can shutoff the water supply to the water heaterwhen a leak is detected. In one embodiment, the shutoff valve iscontrolled by the sensor unit 102. In one embodiment, the sensor unit102 receives instructions from the base unit 112 to shut off the watersupply to the heater 801. In one embodiment, the responsible party 120sends instructions to the monitoring computer 113 instructing themonitoring computer 113 to send water shut off instructions to thesensor unit 102. Similarly, in one embodiment, the sensor unit 102controls a gas shutoff valve 811 to shut off the gas supply to the waterheater 801 and/or to a furnace (not shown) when dangerous conditions(such as, for example, gas leaks, carbon monoxide, etc.) are detected.In one embodiment, a gas detector 812 is provided to the sensor unit102. In one embodiment, the gas detector 812 measures carbon monoxide.In one embodiment, the gas detector 812 measures flammable gas, such as,for example, natural gas or propane.

In one embodiment, an optional temperature sensor 818 is provided tomeasure stack temperature. Using data from the temperature sensor 818,the sensor unit 102 reports conditions, such as, for example, excessstack temperature. Excess stack temperature is often indicative of poorheat transfer (and thus poor efficiency) in the water heater 818.

In one embodiment, an optional temperature sensor 819 is provided tomeasure temperature of water in the water heater 810. Using data fromthe temperature sensor 819, the sensor unit 102 reports conditions, suchas, for example, over-temperature or under-temperature of the water inthe water heater.

In one embodiment, an optional current probe 821 is provided to measureelectric current provided to a heating element 820 in an electric waterheater. Using data from the current probe 821, the sensor unit 102reports conditions, such as, for example, no current (indicating aburned-out heating element 820). An over-current condition oftenindicates that the heating element 820 is encrusted with mineraldeposits and needs to be replaced or cleaned. By measuring the currentprovided to the water heater, the monitoring system can measure theamount of energy provided to the water heater and thus the cost of hotwater, and the efficiency of the water heater.

In one embodiment, the sensor 803 includes a moisture sensor. Using datafrom the moisture sensor, the sensor unit 102 reports moistureconditions, such as, for example, excess moisture that would indicate awater leak, excess condensation, etc.

In one embodiment, the sensor unit 102 is provided to a moisture sensor(such as the sensor 803) located near an air conditioning unit. Usingdata from the moisture sensor, the sensor unit 102 reports moistureconditions, such as, for example, excess moisture that would indicate awater leak, excess condensation, etc.

In one embodiment, the sensor 201 includes a moisture sensor. Themoisture sensor can be place under a sink or a toilet (to detectplumbing leaks) or in an attic space (to detect roof leaks).

Excess humidity in a structure can cause severe problems such asrotting, growth of molds, mildew, and fungus, etc. (hereinafter referredto generically as fungus). In one embodiment, the sensor 201 includes ahumidity sensor. The humidity sensor can be place under a sink, in anattic space, etc. to detect excess humidity (due to leaks, condensation,etc.). In one embodiment, the monitoring computer 113 compares humiditymeasurements taken from different sensor units in order to detect areasthat have excess humidity. Thus, for example, the monitoring computer113 can compare the humidity readings from a first sensor unit 102 in afirst attic area, to a humidity reading from a second sensor unit 102 ina second area. For example, the monitoring computer can take humidityreadings from a number of attic areas to establish a baseline humidityreading and then compare the specific humidity readings from varioussensor units to determine if one or more of the units are measuringexcess humidity. The monitoring computer 113 would flag areas of excesshumidity for further investigation by maintenance personnel. In oneembodiment, the monitoring computer 113 maintains a history of humidityreadings for various sensor units and flags areas that show anunexpected increase in humidity for investigation by maintenancepersonnel.

In one embodiment, the monitoring system 100 detects conditionsfavorable for fungus (e.g., mold, mildew, fungus, etc.) growth by usinga first humidity sensor located in a first building area to producefirst humidity data and a second humidity sensor located in a secondbuilding area to produce second humidity data. The building areas canbe, for example, areas near a sink drain, plumbing fixture, plumbing,attic areas, outer walls, a bilge area in a boat, etc.

The monitoring station 113 collects humidity readings from the firsthumidity sensor and the second humidity sensor and indicates conditionsfavorable for fungus growth by comparing the first humidity data and thesecond humidity data. In one embodiment, the monitoring station 113establishes a baseline humidity by comparing humidity readings from aplurality of humidity sensors and indicates possible fungus growthconditions in the first building area when at least a portion of thefirst humidity data exceeds the baseline humidity by a specified amount.In one embodiment, the monitoring station 113 establishes a baselinehumidity by comparing humidity readings from a plurality of humiditysensors and indicates possible fungus growth conditions in the firstbuilding area when at least a portion of the first humidity data exceedsthe baseline humidity by a specified percentage.

In one embodiment, the monitoring station 113 establishes a baselinehumidity history by comparing humidity readings from a plurality ofhumidity sensors and indicates possible fungus growth conditions in thefirst building area when at least a portion of the first humidity dataexceeds the baseline humidity history by a specified amount over aspecified period of time. In one embodiment, the monitoring station 113establishes a baseline humidity history by comparing humidity readingsfrom a plurality of humidity sensors over a period of time and indicatespossible fungus growth conditions in the first building area when atleast a portion of the first humidity data exceeds the baseline humidityby a specified percentage of a specified period of time.

In one embodiment, the sensor unit 102 transmits humidity data when itdetermines that the humidity data fails a threshold test. In oneembodiment, the humidity threshold for the threshold test is provided tothe sensor unit 102 by the monitoring station 113. In one embodiment,the humidity threshold for the threshold test is computed by themonitoring station from a baseline humidity established in themonitoring station. In one embodiment, the baseline humidity is computedat least in part as an average of humidity readings from a number ofhumidity sensors. In one embodiment, the baseline humidity is computedat least in part as a time average of humidity readings from a number ofhumidity sensors. In one embodiment, the baseline humidity is computedat least in part as a time average of humidity readings from a humiditysensor. In one embodiment, the baseline humidity is computed at least inpart as the lesser of a maximum humidity reading an average of a numberof humidity readings.

In one embodiment, the sensor unit 102 reports humidity readings inresponse to a query by the monitoring station 113. In one embodiment,the sensor unit 102 reports humidity readings at regular intervals. Inone embodiment, a humidity interval is provided to the sensor unit 102by the monitoring station 113.

In one embodiment, the calculation of conditions for fungus growth iscomparing humidity readings from one or more humidity sensors to thebaseline (or reference) humidity. In one embodiment, the comparison isbased on comparing the humidity readings to a percentage (e.g.,typically a percentage greater than 100%) of the baseline value. In oneembodiment, the comparison is based on comparing the humidity readingsto a specified delta value above the reference humidity. In oneembodiment, the calculation of likelihood of conditions for fungusgrowth is based on a time history of humidity readings, such that thelonger the favorable conditions exist, the greater the likelihood offungus growth. In one embodiment, relatively high humidity readings overa period of time indicate a higher likelihood of fungus growth thanrelatively high humidity readings for short periods of time. In oneembodiment, a relatively sudden increase in humidity as compared to abaseline or reference humidity is reported by the monitoring station 113as a possibility of a water leak. If the relatively high humidityreading continues over time then the relatively high humidity isreported by the monitoring station 113 as possibly being a water leakand/or an area likely to have fungus growth or water damage.

Temperatures relatively more favorable to fungus growth increase thelikelihood of fungus growth. In one embodiment, temperature measurementsfrom the building areas are also used in the fungus grown-likelihoodcalculations. In one embodiment, a threshold value for likelihood offungus growth is computed at least in part as a function of temperature,such that temperatures relatively more favorable to fungus growth resultin a relatively lower threshold than temperatures relatively lessfavorable for fungus growth. In one embodiment, the calculation of alikelihood of fungus growth depends at least in part on temperature suchthat temperatures relatively more favorable to fungus growth indicate arelatively higher likelihood of fungus growth than temperaturesrelatively less favorable for fungus growth. Thus, in one embodiment, amaximum humidity and/or minimum threshold above a reference humidity isrelatively lower for temperature more favorable to fungus growth thanthe maximum humidity and/or minimum threshold above a reference humidityfor temperatures relatively less favorable to fungus growth.

In one embodiment, a water flow sensor is provided to the sensor unit102. The sensor unit 102 obtains water flow data from the water flowsensor and provides the water flow data to the monitoring computer 113.The monitoring computer 113 can then calculate water usage.Additionally, the monitoring computer can watch for water leaks, by, forexample, looking for water flow when there should be little or no flow.Thus, for example, if the monitoring computer detects water usagethroughout the night, the monitoring computer can raise an alertindicating that a possible water leak has occurred.

In one embodiment, the sensor 201 includes a water flow sensor isprovided to the sensor unit 102. The sensor unit 102 obtains water flowdata from the water flow sensor and provides the water flow data to themonitoring computer 113. The monitoring computer 113 can then calculatewater usage. Additionally, the monitoring computer can watch for waterleaks, by, for example, looking for water flow when there should belittle or no flow. Thus, for example, if the monitoring computer detectswater usage throughout the night, the monitoring computer can raise analert indicating that a possible water leak has occurred.

In one embodiment, the sensor 201 includes a fire-extinguisher tampersensor is provided to the sensor unit 102. The fire-extinguisher tampersensor reports tampering with or use of a fire-extinguisher. In oneembodiment the fire-extinguisher temper sensor reports that the fireextinguisher has been removed from its mounting, that a fireextinguisher compartment has been opened, and/or that a safety lock onthe fire extinguisher has been removed.

In one embodiment, the sensor unit 102 is configured as anadjustable-threshold sensor that computes a threshold level. In oneembodiment, the threshold is computed as an average of a number ofsensor measurements. In one embodiment, the average value is arelatively long-term average. In one embodiment, the average is atime-weighted average wherein recent sensor readings used in theaveraging process are weighted differently than less recent sensorreadings. In one embodiment, more recent sensor readings are weightedrelatively more heavily than less recent sensor readings. In oneembodiment, more recent sensor readings are weighted relatively lessheavily than less recent sensor readings. The average is used to set thethreshold level. When the sensor readings rise above the thresholdlevel, the sensor indicates a notice condition. In one embodiment, thesensor indicates a notice condition when the sensor reading rises abovethe threshold value for a specified period of time. In one embodiment,the sensor indicates a notice condition when a statistical number ofsensor readings (e.g., 3 of 2, 5 of 3, 10 of 7, etc.) are above thethreshold level. In one embodiment, the sensor unit 102 indicatesvarious levels of alarm (e.g., warning, alert, alarm) based on how farabove the threshold the sensor reading has risen.

In one embodiment, the sensor unit 102 computes the notice levelaccording to how far the sensor readings have risen above the thresholdand how rapidly the sensor readings have risen. For example, forpurposes of explanation, the level of readings and the rate of rise canbe quantified as low, medium, and high. The combination of sensorreading level and rate of rise then can be show as a table, as show inTable 1. Table 1 provides examples and is provided by way ofexplanation, not limitation. TABLE 1 Sensor Reading Level (as comparedto the threshold) Rate High Warning Alarm Alarm of Rise Medium NoticeWarning Alarm Low Notice Warning Alarm Low Medium High

One of ordinary skill in the art will recognize that the notice level Ncan be expressed as an equation N=f(t, v, r), where t is the thresholdlevel, v is the sensor reading, and r is the rate of rise of the sensorreading. In one embodiment, the sensor reading v and/or the rate of riser are lowpass filtered in order to reduce the effects of noise in thesensor readings. In one embodiment, the threshold is computed by lowpassfiltering the sensor readings v using a filter with a relatively lowcutoff frequency. A filter with a relatively low cutoff frequencyproduces a relatively long-term averaging effect. In one embodiment,separate thresholds are computed for the sensor reading and for the rateof rise.

In one embodiment, a calibration procedure period is provided when thesensor unit 102 is powered up. During the calibration period, the sensordata values from the sensor 201 are used to compute the threshold value,but the sensor does not compute notices, warnings, alarms, etc., untilthe calibration period is complete. In one embodiment, the sensor unit102 uses a fixed (e.g., pre-programmed) threshold value to computenotices, warnings, and alarms during the calibration period and thenuses the adjustable threshold value once the calibration period hasended.

In one embodiment, the sensor unit 102 determines that a failure of thesensor 201 has occurred when the adjustable threshold value exceeds amaximum adjustable threshold value. In one embodiment, the sensor unit102 determines that a failure of the sensor 201 has occurred when theadjustable threshold value falls below a minimum adjustable thresholdvalue. The sensor unit 102 can report such failure of the sensor 201 tothe base unit 112.

In one embodiment, the sensor unit 102 obtains a number of sensor datareadings from the sensor 201 and computes the threshold value as aweighted average using a weight vector. The weight vector weights somesensor data readings relatively more than other sensor data readings.

In one embodiment, the sensor unit 102 obtains a number of sensor datareadings from the sensor unit 201 and filters the sensor data readingsand calculates the threshold value from the filtered sensor datareadings. In one embodiment, the sensor unit applies a lowpass filter.In one embodiment, the sensor unit 201 uses a Kalman filter to removeunwanted components from the sensor data readings. In one embodiment,the sensor unit 201 discards sensor data readings that are “outliers”(e.g., too far above or too far below a normative value). In thismanner, the sensor unit 102 can compute the threshold value even in thepresence of noisy sensor data.

In one embodiment, the sensor unit 102 indicates a notice condition(e.g., alert, warning, alarm) when the threshold value changes toorapidly. In one embodiment, the sensor unit 102 indicates a noticecondition (e.g., alert, warning, alarm) when the threshold value exceedsa specified maximum value. In one embodiment, the sensor unit 102indicates a notice condition (e.g., alert, warning, alarm) when thethreshold value falls below a specified minimum value.

In one embodiment, the sensor unit 102 adjusts one or more operatingparameters of the sensor 201 according the threshold value. Thus, forexample, in the example of an optical smoke sensor, the sensor unit 201can reduce the power used to drive the LED in the optical smoke sensorwhen the threshold value indicates that the optical smoke sensor can beoperated at lower power (e.g., low ambient light conditions, cleansensor, low air particulate conditions, etc.). The sensor unit 201 canincrease the power used to drive the LED when the threshold valueindicates that the optical smoke sensor should be operated at higherpower (e.g., high ambient light, dirty sensor, higher particulates inthe air, etc.).

In one embodiment, an output from a Heating Ventilating and/or AirConditioning (HVAC) system 350 is optionally provided to the sensor unit102 as shown in FIG. 2. In one embodiment, an output from the HVACsystem 350 is optionally provided to the repeater 110 as shown in FIG. 3and/or to the monitoring system 113 as shown in FIG. 4. In this manner,the system 100 is made aware of the operation of the HVAC system. Whenthe HVAC system turns on or off, the airflow patterns in the roomchange, and thus the way in which smoke or other materials (e.g.,flammable gases, toxic gases, etc.) changes as well. Thus, in oneembodiment, the threshold calculation takes into account the airfloweffects caused by the HVAC system. In one embodiment, an adaptivealgorithm is used to allow the sensor unit 102 (or monitoring system113) to “learn” how the HVAC system affects sensor readings and thus thesensor unit 102 (or monitoring system 113) can adjust the thresholdlevel accordingly. In one embodiment, the threshold level is temporarilychanged for a period of time (e.g., raised or lowered) to avoid falsealarms when the HVAC system turns on or off. Once the airflow patternsin the room have re-adjusted to the HVAC state, then the threshold levelcan be re-established for desired system sensitivity.

Thus, for example, in one embodiment where an averaging or lowpassfilter type process is used to establish the threshold level, thethreshold level is temporarily set to de-sensitize the sensor unit 102when the HVAC system turns on or off, thus allowing the averaging orlowpass filtering process to establish a new threshold level. Once a newthreshold level is established (or after a specified period of time),then the sensor unit 102 returns to its normal sensitivity based on thenew threshold level.

In one embodiment, the sensor 201 is configured as an infrared sensor.In one embodiment, the sensor 201 is configured as an infrared sensor tomeasure a temperature of objects within a field of view of the sensor201. In one embodiment, the sensor 201 is configured as an infraredsensor. In one embodiment, the sensor 201 is configured as an infraredsensor to detect flames within a field of view of the sensor 201. In oneembodiment, the sensor 201 is configured as an infrared sensor.

In one embodiment, the sensor 201 is configured as an imaging sensor. Inone embodiment, the controller 202 is configured to detect flames byprocessing of image data from the imaging sensor.

FIG. 9 shows an example of one embodiment of a PMU. The PMU 125 includesa PMU housing 905 covering electronic components (not shown). A screen903 is attached to the front of PMU casing 905. PMU casing 905 can alsooptionally have PMU function keys such as, for example, ACKNOWLEDGEbutton 907, OK button 909, PERFORM DIAGNOSTIC CHECK button 911, CALLFIRE DEPARTMENT button 913, CALL TENANT button 915, ALERT OTHERS button917, POWER ON/OFF button 919 and TALK button 921 as well as cursorcontroller 923 and volume controller 925.

The screen 903 can be in color or monotone. The screen 903 can have backlights in order to allow viewing in the dark. The screen 903 can be anyscreen used for displaying an electronic signal such as, for example,LCD, LED, color LCD, etc. In one embodiment, the screen 903 can replaceone or all of the buttons through the use of a touch screen display. Inone embodiment, the PMU 125 can use voice recognition in addition to, orinstead of the buttons. In one embodiment, the PMU 125 can use acombination of touch screen display, buttons, and voice recognition.

In one embodiment, the PMU function keys can include an ACKNOWLEDGEbutton 907, an OK button 909, a PERFORM DIAGNOSTIC CHECK button 911, aCALL FIRE DEPARTMENT button 913, a CALL TENANT button 915, an ALERTOTHERS button 917, a POWER ON/OFF button 919, or a TALK BUTTON 921. PMUfunction keys can also include other control keys that would be usefulin a building or complex monitoring system 113. The PMU function keyscan be located in any convenient location on the PMU casing 905, and canbe of any color, shape, size, or material. In addition, any combination,including only one or none of the PMU function keys can be incorporatedinto a PMU 125.

The ACKNOWLEDGE button 907 instructs the PMU 125 to send a response backto the monitoring computer 113 that the user has acknowledged receipt ofthe communication. The OK button 909 instructs the PMU 125 to send aresponse back to the monitoring computer 113 that the user hasinvestigated the situation has determined that the situation is a falsealarm or is resolved. The CALL FIRE DEPARTMENT button 913 instructs thePMU 125 to send a response back to the monitoring computer 113instructing the monitoring computer 113 to call the local firedepartment and request assistance. In one embodiment, the CALL FIREDEPARTMENT button 913 can also instruct the PMU 125 to connect the userdirectly to the fire department through a secondary transceiver 1313configured to make regular telephone or cellular calls. In oneembodiment, the CALL FIRE DEPARTMENT button 913 can instruct the PMU 125to send a response to the monitoring computer 113 to call the firedepartment and to connect the PMU 125 to the fire department, so thatthe user can speak directly to the fire department without the need fora secondary transceiver 1313 in the PMU 125. In this embodiment, themonitoring computer 113 acts as a repeater between a telephoneconnection with the fire department and a radio frequency transmission,or other type of transmission from the PMU 125.

The CALL TENANT button 915 can instruct the PMU 125 to send aninstruction to the monitoring computer 113 to call the tenant oroccupant of the unit in which the sensor is located to see if the unithas occupants. In one embodiment, the CALL TENANT button 915 instructsthe monitoring computer to call the occupants of the unit and thenconnect the PMU 125 device directly to the tenants through transceiver1309. In one embodiment, the CALL TENANT button 915 instructs the PMU125 to directly call the tenant through secondary transceiver 1313,thereby allowing the PMU user to talk directly with the tenant.

The ALERT OTHERS button 917 can instruct the PMU 125 to send aninstruction to the monitoring computer 113 to contact other PMUs orother management through other devices (e.g. telephone, cell phone, fax,internet, etc.). In one embodiment, the ALERT OTHERS button 917 can alsoinstruct the monitoring computer 113 to connect the PMU user to others(e.g., nearby apartments, other PMU users, management using otherdevices) that the monitoring computer contacts in order to discuss thesituation. In one embodiment, the ALERT OTHERS button 917 can instructthe PMU 125 to directly contact other management through use ofsecondary transceiver 1313.

The POWER ON/OFF button 919 can instruct the PMU 125 to power up when ithas been powered down, or alternatively to power down when it has beenpowered up in order to conserve energy. The TALK button 921 works inconjunction with a walkie talkie system that can be incorporated intothe PMU 125. The TALK button 919 can either work in conjunction with thetransceiver 1309, or with the secondary transceiver 1313. The TALKbutton 921 instructs the PMU 125 to send the electrical signal from themicrophone 1303 to other local transceivers configured to receive thesignal.

The CURSOR CONTROLER button 923 can instruct the PMU 125 to move thecurser on the screen either up or down or side to side in order tonavigate through the entire message sent from the monitoring computer113. In addition, the CURSOR CONTROLER button 923 can also allow a userto select certain information on the screen for additional use. TheVOLUME button(s) 925 can be used to adjust the volume of the PMU 125.

The PERFORM DIAGNOSTIC CHECK button 911 instructs the PMU 125 to send amessage to the monitoring computer 113 to run a diagnostic check on thesensor system. When the diagnostic check has been completed, themonitoring computer 113 then sends a communication to the PMU 125containing the results of the diagnostic check.

In one embodiment, the PMU 125 can require the user to enter a passwordor pass code to identify the user. In this way, multiple users can usethe same PMU. In addition, the monitoring computer 113 can alsooptionally be used to keep track of a user's movement throughout theday, as well as keeping a record of what the user's are doing. In oneembodiment, different tasks can require different levels of clearance.For instance, a separate password or pass code can be required toprogram the sensors using the PMU 125.

Although FIG. 9 shows specific buttons, one of ordinary skill in the artwill recognize that other buttons and/or a general keypad can beprovided. In one embodiment, the screen 903 is used to provided menuoptions and the cursor controller 923 is used to navigate among the menuitems and select menu items.

In one embodiment, the PMU 125 can be used to read the threshold levelof various sensors and/or the sensor readings of the sensors. In oneembodiment, when a sensor alert is sent to the PMU 125, the PMU 125displays the sensor threshold level, and the sensor reading level(and/or the amount the sensor reading is above the threshold level.). Inone embodiment, the PMU 125 displays a map of other sensors in thevicinity of the sensor sending the alert and the readings from thesensors in the vicinity of the sensor sending the alert.

In one embodiment, the user of the PMU 125 can select a sensor andchange the sensor threshold value. Thus, for example, if a sensor isgiving false alerts, the user of the PMU 125 can adjust the thresholdlevel of the sensor to reduce the sensitivity of the sensor.Alternatively, if a first sensor in an apartment is sending an alert,the user of the PMU 125 can use the PMU 125 to change the thresholdlevel (e.g., increase the sensitivity) of other sensors in the apartmentor in nearby apartments.

In one embodiment the PMU 125 can display a map (e.g., a contour map,colorized map, etc.) of the sensors in the sensor system showingsensitivity, threshold value, battery value, sensor readings, etc. andthus provide the user with an overall picture of the sensor system.

FIGS. 10-12 show examples of various embodiments of communicationsreceived by the PMU 125. FIG. 10 graphically shows one embodiment of analert message. The alert message is displayed on screen 1003 of PMU 125and can include any relevant information about the alert. Relevantinformation can include any of the following: rate of rise oftemperature or smoke, apartment number or unit number, which room(s) inthe apartment the sensor(s) are located, the number of the sensorsindicating an alert, the phone number of the occupants, whether or notothers have been notified and/or whether others have acknowledgedreceipt of the notification, as well as any other update informationrelevant in assessing the situation.

FIG. 11 graphically shows one embodiment of a warning communication. Thewarning message can be displayed on screen 1103 of PMU 125. The warningmessage can contain information such as a sensor warning that it needs anew battery, a warning that a sensor has been tampered with, a warningthat the heating, air conditioning or ventilation system needsmaintenance or that a particular unit is not functioning properly, awarning that a water leak has been detected, or any other informationrelevant in maintaining a building or complex.

FIG. 12 graphically represents a communication in which a diagnosticcheck has been run. The diagnostic check can be displayed on screen 1203of PMU 125. The diagnostic check communication can contain suchinformation as the working status of each sensor, whether anymaintenance is required on a sensor (e.g. needs new battery or is notfunctioning properly and needs repair or replacement). The diagnosticcheck can also contain information on the repeaters, the heatingventilation and air conditioning system, as well as diagnosticinformation on any other systems relevant in maintaining a building orcomplex.

Referring to FIGS. 10-12, the PMU 125 can indicate an alarm, warning,notice, or other communication. For instance, In one embodiment, anemergency alarm message can cause the PMU 125 to sound a loud beep,series of beeps, a horn, or any other noise designed to catch theattention of the user. In one embodiment, the PMU 125 can vibrate orflash lights to catch the attention of the user. In one embodiment, thePMU 125 can give an audible message, such as “SMOKE DETECTED IN APT.33.” Other types of communications, such as a warning, can be indicatedin different ways, for instance a different type of audible sound. Thevolume of the auditory alerts can change depending on the severity ofthe condition. Different colors of lights can flash, or more or fewerlights can flash. In addition, the duration of the message indicatorscan be prolonged or shortened depending on the priority level of thecondition.

Text displayed on the PMU screen 903 can also be suitably configured toconvey the necessary information to building management. For instance,some or all of the words displayed on the screen can flash. Key wordscan be highlighted. For example, key information can be enlarged,bolded, displayed in different colors, or otherwise configured to grabthe attention of the PMU user. In one embodiment, the screen can be toosmall to display all of the text of the message at the same time. Insuch cases, a cursor controller, such as cursor controller 923, can beused to scroll through the entirety of the message. Graphics can also bedisplayed on the screen along with the text or as a splash screenindicating the type of message that has been received before a userlooks at the text of the message. In one embodiment, a user can berequired to push a function key, such as ACKNOWLEDGE button 907 beforethe full text of the message is displayed on the screen. In addition,any advantageous modification to the text or graphics to be displayedcan be incorporated into the display.

FIG. 13 is a block diagram of a PMU 125. In one embodiment, the PMU 125includes a transceiver 1309 for communication between the sensor systemand the controller 1311. The controller 1311 typically provides power,data, and control information to the transceiver 1309. A power source1315 is provided to the controller 1311. The controller 1311 can alsooptionally receive and/or send electronic signals from a microphone1303, user inputs 1305, a sensor programming interface 1301, a computerinterface 1321, a location detector 1307, or a second transceiver 1313.

The microphone 1303 can be a microphone of any type which receivesauditory noises and transmits an electronic signal representing theauditory noises. The user inputs 1305 can include any button or userinput device for communicating an instruction to the controller 1311.The computer interface 1321 is used to provide communication between thePMU 125 and a computer system (e.g., the monitoring computer 113). Thecomputer interface 1321 can be a standard computer data interface, suchas, for example, Ethernet, wireless Ethernet, firewire port, UniversalSerial Bus (USB) port, Bluetooth, etc. A location detector 1307 canprovide location and/or movement details of the PMU 125. The locationdetector 1307 can be any location or motion sensing system, such as, forexample, a Global Positioning System (GPS) or an accelerometer fordetecting movement. A second transceiver 1313 can be provided forsecondary communication channels. The second transceiver 1313 cancommunicate with any known communication network such as, for example,wireless Ethernet, cellular telephone, or Bluetooth.

The sensor programming interface 1301 can be used to enter or readprogramming information from the sensor units such as, for example, IDcode, location code, software updates, etc. In one embodiment, the PMUprogramming interface 1301 can be designed to communicate to all thesensors in a sensor system at the same time. In one embodiment, thesensor programming interface 1301 can be designed so that the PMU 125can communicate with a selected sensor or group of sensors. Forinstance, the sensor interface 1301 can be designed so that the PMU 125must be close to the sensor in order to communicate with the sensor.This can be accomplished by designing the sensor programming interface1301 with optical communications, such as, for example, an infra red(IR) transmitter, or designing the sensor programming interface 601 witha hardwire communication, such as through a wire connection directlywith a sensor.

FIG. 14 is a flow chart of one embodiment showing how the PMU 125communicates with the sensor system. The operation of the sensor systemin communication with the PMU 125 begins at block 1401 where the PMU 125is powered up. The PMU 125 next advances to block 1403 where the PMU 125goes through an initialization (e.g. establishes communications withmonitoring computer 113, uploads software, etc.). The PMU 125 thenadvances to block 1405 in which it listens for any communications fromthe monitoring computer 113. At block 1407, the PMU 125 decides whetherinformation has been received. If information has been received, the PMU125 advances to block 1409, otherwise, the PMU 125 goes back to block1405 and listens for any communications. If information is received andthe PMU 125 advances to block 1409, the PMU processes the information.

At decision block 1411, the PMU 125 decides if the information is analert. If the information is an alert, then the PMU 125 advances todecision block 1419, otherwise, the PMU 125 advances to block 1413. Atblock 1413, the PMU 125 decides whether or not an abnormal conditioncommunication or diagnostic check communication has been received. Ifthere is an abnormal condition or diagnostic check, the PMU 125 advancesto block 1421. Otherwise the PMU 125 advances to decision block 1415. Atdecision block 1415, the PMU 125 decides whether or not the user hasinputted an instruction. If there has been a user-inputted instruction,then the PMU 125 moves on to block 1417, otherwise, it goes back toblock 1405 and listens for the instruction. At block 1417, the PMU 125performs the instruction or transmits the instructions back to themonitoring computer 113.

Returning now to block 1419, at block 1419 the PMU 125 sounds an alarmor displays an alarm and then advances to decision block 1427 where itlooks to see if an acknowledgment has been received. If anacknowledgment has not been received, the PMU 125 advances to decisionblock 1433 where it looks to see if a timeout has elapsed. If a timeouthas not elapsed, the PMU 125 moves back to 1419 where it sounds thealarm and waits for an acknowledgment. If a timeout has elapsed, the PMU125 returns to block 1405 where it listens for instructions from themonitoring computer 113. If at block 1405 an acknowledgment has beenreceived, the PMU 125 advances to block 1429 where it transmits theacknowledgment and then goes on to block 1423.

Returning now to block 1421, if an abnormal condition or diagnosticcondition is received, then the PMU 125 displays the abnormal conditionor diagnostic check message on the PMU screen 903 and then advances toblock 1423. At block 1423, the PMU 125 waits for instructions. Atdecision block 1425, if an instruction is received, then the PMU 125advances to block 1417. Otherwise, the PMU 125 advances to block 1431where it monitors itself for movement. If there is no movement in thePMU 125, the PMU advances to block 1435 where it transmits a “nomovement” alert to the monitoring computer and then returns to block1405. If there has been movement, the PMU 125 returns to block 1423 andwaits for instructions.

FIG. 15 is a graphical representation of alert priority responses by themonitoring computer 113. In one embodiment, different responses areassigned to different conditions. Priority levels can be based on levelof smoke, gas, water, etc., the amount of time a sensor has beensignaling, the rate of rise of smoke, temperature, gas, water, etc., thenumber of sensors signaling, or any other measurement that would beuseful in assessing the priority level of the situation. For example, asshown in block 1501, if a low priority condition occurs, the monitoringcomputer 113 sends information about the condition to the PMU 125, andno further action is taken by the monitoring computer 113 with respectto communicating with the PMU 125. In an elevated priority condition, asshown in block 1503, the monitoring computer 113 sends information onthe condition to the PMU 125 and then waits for acknowledgment and/or aresponse. If the monitoring computer 113 does not receive anacknowledgment or response, it will attempt to contact other PMUs or itcan attempt to contact management through other channels (e.g.telephone, cell phone, fax, email, etc.). If the monitoring computer 113receives an acknowledgement, but then receives a “no movement” alertfrom the PMU 125, the monitoring computer 113 will attempt to contactother PMUs or it can attempt to contact management through otherchannels. In a high priority condition, as shown in block 1505, themonitoring computer 113 can immediately send the information to multiplePMUs and can immediately attempt to contact management through otherchannels (e.g., telephone, cell phone, fax, email, etc.) and can wait arelatively short period of time for acknowledgment and responses beforecontacting the fire department directly. In a severe priority condition,as shown in block 1507, the monitoring computer can directly andimmediately call the fire department and then can immediately attempt tocontact all PMUs and all other management contacts. It will beunderstood by those of skill in the art that the responses andconditions of FIG. 15 are only one example and are not made by way oflimitation. In addition, those of skill in the art that In oneembodiment all conditions can be sent with the same priority level.

In one embodiment, neighboring unit occupants will also be notified ofan occurring situation. For instance, in the case of a water leak, theoccupants of the units located below the unit indicating a water leakwould be notified that a unit above them has a water leak so that theycan take precautions. Occupants of other units located above, below,adjacent to, or near a unit with a sensor signaling a situation can alsobe notified to the situation so that they can take appropriateprecautions and/or provide more immediate assistance or help (e.g.,water leak, fire/smoke detected, carbon monoxide detected, etc.). In oneembodiment, the monitoring computer includes a database indicating therelative locations of the various sensor units 102 so that themonitoring computer 113 it knows which units to notify in the event asituation does occur. Thus, for example, the monitoring computer can beprogrammed so that it knows units 201 and 101 are below unit 301, orthat unit 303 is adjacent to unit 301 and unit 302 is across the hall,etc. In one embodiment, the monitoring system 113 knows which sensorsare in which apartments and the relative positions of the variousapartments (e.g., which apartments are above other, adjacent to others,etc.). In one embodiment, the monitoring system 113 database includesinformation about sensor locations in various apartments relative toother apartments (e.g., sensor 1 in apartment 1 is on the wall oppositesensor 3 in apartment 2, etc.).

It will be evident to those skilled in the art that the invention is notlimited to the details of the foregoing illustrated embodiments and thatthe invention can be embodied in other specific forms without departingfrom the spirit or essential attributes thereof, furthermore, variousomissions, substitutions and changes can be made without departing fromthe spirit of the invention. For example, although specific embodimentsare described in terms of the 900 MHz frequency band, one of ordinaryskill in the art will recognize that frequency bands above and below 900MHz can be used as well. The wireless system can be configured tooperate on one or more frequency bands, such as, for example, the HFband, the VHF band, the UHF band, the Microwave band, the Millimeterwave band, etc. One of ordinary skill in the art will further recognizethat techniques other than spread spectrum can also be used. Themodulation is not limited to any particular modulation method, such thatmodulation scheme used can be, for example, frequency modulation, phasemodulation, amplitude modulation, combinations thereof, etc. Theforegoing description of the embodiments is, therefore, to be consideredin all respects as illustrative and not restrictive, with the scope ofthe invention being delineated by the appended claims and theirequivalents.

1. A sensor system, comprising: one or more sensor units, each of saidone or more sensor units comprising at least one sensor configured tomeasure a condition, said sensor unit configured to receiveinstructions, said sensor unit configured to report a severity offailure value when said sensor determines that data measured by said atleast one sensor fails a threshold test, said sensor unit configured toadjust said threshold from time to time according to sensor readingtaken during a specified time period; a base unit configured tocommunicate with said one or more sensor units to a monitoring computer,said monitoring computer configured to send a notification to aresponsible party when said severity of failure value corresponds to anemergency condition, said monitoring computer configured to log datafrom one or more of said sensor units when said data from one or more ofsaid sensor units corresponds to a severity of failure value; and aportable monitoring unit comprising: a controller in communication withsaid one or more sensors, said controller configured to allow a user ofsaid portable monitoring unit to remotely set a sensor threshold levelof said one or more sensor units, said controller further configured toreceive one or more actual sensor data threshold levels from said one ormore sensor units; a display; one or more input devices; and atransceiver configured to provide communication between a sensor systemand said controller.
 2. The portable monitoring unit of claim 1, whereinthe sensor system sends said information upon the occurrence of apre-defined event.
 3. The portable monitoring unit of claim 1, whereinthe sensor system sends said information upon request from saidcontroller.
 4. The portable monitoring unit of claim 1, wherein saidmeasured conditions further comprises a working status of said sensors.5. The portable monitoring unit of claim 1, wherein said controller isfurther configured to receive diagnostic information and display saiddiagnostic information on said display.
 6. The portable monitoring unitof claim 1, wherein input devices comprises buttons.
 7. The portablemonitoring unit of claim 1, further comprising a microphone.
 8. Theportable monitoring unit of claim 1, further comprising an audio device.9. The portable monitoring unit of claim 1, further comprising a sensorprogramming unit.
 10. The portable monitoring unit of claim 1, furthercomprising a second transceiver.
 11. The portable monitoring unit ofclaim 10, wherein said second transceiver is configured to communicatethrough cellular telephone.
 12. The portable monitoring unit of claim10, wherein said second transceiver is configured to communicate throughradio transmissions.
 13. The portable monitoring unit of claim 1,further comprising a location detector unit.
 14. The portable monitoringunit of claim 1, further comprising a computer interface.
 15. A sensorsystem, comprising: one or more sensor units, each of said one or moresensor units comprising at least one sensor configured to measure acondition, said sensor unit configured to report a severity of failurevalue when said sensor determines that data measured by said at leastone sensor fails a threshold test; and a base unit configured tocommunicate with said one or more sensor units to a monitoring computer;and a portable monitoring unit configured to communicate with saidmonitoring computer; wherein said portable monitoring unit is configuredto remotely set a sensor threshold level of said one or more sensorunits, and wherein said portable monitoring unit is configured todisplay actual sensor data threshold levels.
 16. The sensor system ofclaim 15, wherein said portable monitoring unit is configured tocommunicate with said monitoring computer through said base unit. 17.The sensor system of claim 15, wherein said portable monitoring unit isconfigured to communicate with said sensor units.
 18. The sensor systemof claim 15, wherein said portable monitoring unit is configured tocommunicate wirelessly with said monitoring computer.
 19. A method ofreporting a condition present in a building or complex, said methodcomprising: reporting a severity of failure condition measured by asensor to a monitoring computer; and sending a notification of saidreported severity of failure condition to a portable monitoring unit,wherein said portable monitoring unit is capable of remotely setting asensor threshold level, and wherein said portable monitoring unit iscapable of displaying actual sensor data threshold levels.
 20. Themethod of claim 19, wherein said portable monitoring unit communicateswith said monitoring computer through said base unit.
 21. The method ofclaim 19, wherein said portable monitoring unit communicates directlywith said sensor units.
 22. The method of claim 19, wherein saidmonitoring computer evaluates a priority level of said reported severityof failure condition to determine what type of notification to send tosaid portable monitoring computer.
 23. The method of claim 22, whereinsaid monitoring computer waits for a response from said portablemonitoring unit and attempts to notify responsible parties through othercommunication channels if said response is not received.
 24. The methodof claim 22, wherein said monitoring computer logs said severity offailure condition and communicates said severity of failure condition tosaid portable monitoring unit upon the occurrence of a predefined event.25. The method of claim 19, wherein said monitoring computer reportssaid severity of failure condition to a fire fighting unit.